The disclosure relates to emergency supplemental power supplies for aeronautical applications, and more particularly to a ram air turbine for generating emergency supplemental power for aircraft in flight.
A Ram Air Turbine (RAT) is a device for generating emergency supplemental power in a wide variety of aircraft. A RAT may generate hydraulic power, electric power, or both. A RAT incorporates a turbine that extracts power from an air stream proximate to the aircraft in flight. The turbine is coupled to suitable power generating equipment, such as a hydraulic pump for hydraulic power and an electric generator for electric power.
The placement of a RAT on some aircraft is such that the aircraft landing gear deployment causes the landing gear to pass in front of the RAT, thereby blocking incoming airflow to the RAT. For RATs that drive a hydraulic pump, the reduction in airflow may cause the RAT to stall. When the RAT stalls, it may continue to rotate at a low speed, typically approximately 800 rpm, such that equilibrium exists between the turbine torque and the load torque.
Once the stall occurs, the RAT may not start back up, even when the landing gear completes its deployment and it no longer blocks the airflow to the RAT.